The present invention is directed to backscatter imaging, and more specifically such imaging utilizing Hadamard transform masking.
One x-ray imaging approach has been Compton backscatter imaging using a flying spot x-ray source and a large x-ray detector on the same side of the target as the source. The collimation methods employed in these systems for scanning the x-ray beam over the target preclude the development of a portable, operationally convenient x-ray camera for on-site examination of large structures. This is primarily due to the competing requirements for a high x-ray fluence exposing the target at each scan position to improve signal to noise ratio for a fixed detector integration time, and the smallest possible diameter x-ray beam to improve the imaging resolution. For mechanical collimation schemes, these conflicting requirements result in high electrical power requirements for x-ray generation and extensive radiation shielding requirements degrading both portability and self-containment.
The present invention overcomes fundamental limitations of x-ray backscatter image formation associated with conventional flying spot spatial modulation of the x-ray beam. In accordance with the present invention, a nonscanning x-ray source is used, which increases incident x-ray fluence at the target by up to five orders of magnitude without requiring intensity modulation of the x-ray source and without any apparent additional thermal management or information degradation. The present invention fulfills the need for a fast, portable, one-sided x-ray backscatter imaging system and method.